TWI706019B - Adhesive tape having foamed-resin base and process for producing the same - Google Patents

Abstract

An adhesive tape having a foamed-resin base comprising closed-cells, and an adhesive layer provided on at least one surface of the foamed-resin base, wherein the average void diameter of the closed-cells is 20 to 180 μm, the maximum void diameter of the closed-cells is 300 μm or less, the dimensional change rate by heating of the adhesive tape is within 100%±5% based on 100% of the dimension before heating, the rubber-elastic elongation recovery rate of the adhesive tape is 85% or more, especially, said adhesive tape has excellent, waterproofness, antistatic property, impact resistance, heat resistance, repairability and flexibility; and a process for producing the same.

Description

Adhesive tape with foamed resin substrate and manufacturing method thereof

The present invention relates to an adhesive tape and a manufacturing method thereof. The adhesive tape has a foamed resin substrate, which is thin and fine but has sufficient characteristics, especially excellent water resistance, electrostatic resistance, and impact resistance. Resistance, heat resistance, repairability and flexibility.

In portable electronic devices such as smart phones and mobile phones, adhesive tapes are used to attach the protective panel of the display to the housing, or to fix other components and modules. Moreover, the waterproofness of the adhesive tape is more important for the waterproofness of portable electronic devices. For example, Patent Documents 1 and 2 disclose waterproof adhesive tapes. Here, a soft foam is used as the base material of the adhesive tape. Because it is thin and has good followability, it is suitable for portable electronic devices. In addition, Patent Document 3 discloses a double-sided adhesive tape that uses a laminate of a foam layer and a reinforcing layer (plastic film) as a base material. The adhesive tape has excellent re-peelability.

In recent years, portable electronic devices have continuously developed large-screen displays, reduced overall products, and improved design. Along with this, not only has the demand for thinner adhesive tapes become stronger, but the demand for narrower bandwidths has also become stronger. For example, the narrowing of the adhesive tape used to connect the protective panel and the shell has been considerably developed. Along with this, it is necessary for the adhesive tape to have a thin and fine foamed resin substrate with excellent water resistance. In addition, the portable electric There are many cases where there is no grounding space in the sub-machine. Therefore, when a user with static electricity touches a portable electronic device, the static electricity may damage the built-in parts through the adhesive tape and fail to operate normally. Therefore, for the adhesive tape, a foamed resin substrate that is thin and finer but has excellent static resistance characteristics becomes a must. In addition, portable electronic devices may be used or placed at high temperatures, or may be subjected to impact, so heat resistance or impact resistance is required. Furthermore, when reattaching fixed parts during the manufacturing process of portable electronic equipment, or when parts are exchanged during repairs, in order to peel off the adhesive tape without problems and easily, the adhesive tape has excellent secondary workability, Or higher repairability becomes necessary.

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent No. 5370796

Patent Document 2: Japanese Patent No. 5477517

Patent Document 3: Japanese Patent Laid-Open No. 2014-037543

The purpose of the present invention is to provide an adhesive tape and its manufacturing method. Although the adhesive tape is thin and thin, it has sufficient characteristics, especially excellent water resistance, static resistance, impact resistance, heat resistance, and repairability. And softness.

The present invention is an adhesive tape having a foamed resin substrate containing closed cells and an adhesive layer provided on at least one side of the foamed resin substrate, and the average diameter of the closed cells is 20~180μm , The maximum diameter is less than 300μm, the upper The heating dimensional change rate of the adhesive tape is within 100%±5% when the size before heating is set to 100%, and the rubber elastic elongation recovery rate of the adhesive tape is more than 85%.

Furthermore, the present invention is a method for manufacturing an adhesive tape, which is used to manufacture the above-mentioned adhesive tape, and has a method of obtaining a foamed resin substrate by forming independent bubbles using thermally expandable microcapsules and/or expanded hollow fillers step.

Since the adhesive tape of the present invention controls the void diameter of the closed cells of the foamed resin substrate to a small size within a specific range, it has excellent water resistance, electrostatic resistance and impact resistance when it is a narrow tape. Furthermore, since the heating dimensional change rate of the adhesive tape is low, it has excellent heat resistance, and the rubber elastic elongation recovery rate is high, so it has excellent repairability.

The manufacturing method of the adhesive tape of the present invention uses thermally expandable microcapsules and/or expanded hollow fillers to form closed cells, so the void diameter of the closed cells in the substrate can be easily controlled to a smaller size within the specified range of the present invention .

1‧‧‧Double-sided adhesive tape

2‧‧‧HV electrode

3‧‧‧Touch pattern analog electrode

4‧‧‧TEG substrate

5‧‧‧Insulation sheet

6‧‧‧SUS system platform

7‧‧‧Acrylic board

Fig. 1 is an optical microscope photograph of one form of independent bubbles in the adhesive tape of the present invention.

Figure 2 is an optical microscope photograph of one of the independent bubbles in the conventional adhesive tape.

Fig. 3 is a schematic diagram for explaining the test method of the anti-static characteristic of the embodiment.

Fig. 4 is a schematic diagram for explaining the test method of the static resistance characteristic of the embodiment.

<Foam resin substrate>

The foamed resin substrate in the present invention is a substrate in which closed cells are formed by foaming the resin. Compared with the foamed resin substrate containing open cells, the foamed resin substrate containing closed cells has better water resistance and artificial sebum and sweat resistance.

In the present invention, the average diameter of the closed cells in the foamed resin substrate is 20 to 180 μm, preferably 30 to 150 μm, and more preferably 40 to 120 μm. In addition, the maximum diameter of the closed cells is 300 μm or less, preferably 250 μm or less, and more preferably 200 μm or less. By controlling the gap diameter to a smaller size within this specific range, the adhesive tape exhibits excellent water resistance, static electricity resistance, and impact resistance even if it is thin and thin.

The measurement of the void diameter is specifically carried out by the following operation: Observe a plurality of isolated bubbles in the 5×5mm area of the foamed resin substrate by an optical microscope using the transmission method, and measure the average value of the void diameter and Maximum value. Fig. 1 is an optical microscope photograph of one form of independent bubbles in the adhesive tape of the present invention. Figure 2 is an optical microscope photograph of one of the independent bubbles in the conventional adhesive tape. According to these photos, it can be clearly seen that the sizes of the independent bubbles of the two are quite different.

In the case where the average diameter is as large as hundreds of μm as shown in Fig. 2 (the conventional technology), large bubbles of the order of 1 to 2 mm may be locally formed. Moreover, this part cannot maintain the shape of independent bubbles, and will become a through state. This penetrating state becomes a major problem in terms of water resistance, static electricity resistance, etc., especially when a narrow-width processed foamed resin substrate adhesive tape is used. In addition, when using a completely bubble-free film substrate, the rigidity of the substrate is relatively high. Therefore, if there is a foreign substance (extra-fine copper wire, etc.) on the bonding surface, swelling will occur in the stepped portion, which will impair the waterproofness. On the other hand, if the If the gap diameter is controlled to a smaller size in a specific range, it is difficult to cause these problems. Even if a higher water pressure is applied, the excellent water resistance can be maintained.

The anti-static properties are generally affected by the type of resin of the foamed resin substrate. When the type of resin is the same, it is believed that the size of the independent bubbles will also affect the anti-static properties. In fact, when the average diameter is as large as hundreds of μm as shown in Figure 2 (the conventional technology), if 15kV of static electricity is applied in the width direction of the narrow-width processed adhesive tape, the foamed resin substrate is easy to The tendency to damage occurs, and the water resistance and other characteristics are impaired. On the other hand, even if the types of resins are the same, as long as the void diameter is controlled to a smaller size in a specific range as shown in FIG. 1 (the present invention), the foamed resin substrate will hardly be broken. Although the reason for the improvement of static resistance is not clear, for example, an increase in the number of resin films between bubbles and bubbles may be one of the main factors. When the resin part interposed between two bubbles is defined as a piece of "resin film", if the porosity is the same, the number of resin films with multiple smaller bubbles is more. Specifically, the number of sheets of the resin film in the form of Fig. 1 (the present invention) is about 10 times or more the number of sheets in Fig. 2 (the prior art). In the present invention, it can be inferred that an increase in the number of such resin films will have a better effect on the improvement of static electricity resistance.

Furthermore, if the void diameter is large as shown in Fig. 2 (the conventional technique), the interlayer failure of the foamed resin substrate is likely to occur due to the impact at low temperature. In addition, film substrates without air bubbles or double-sided adhesive tapes without substrates may also easily cause peeling of the adherend due to impact, and damage to display components such as glass. On the other hand, if the void diameter is controlled to a smaller size within a specific range as in the present invention, impact absorption is improved, and sufficient impact resistance is exhibited even at low temperatures.

As described above, in the present invention, even if higher water pressure is applied, even if static electricity is applied, and even if impact is received, the air bubbles in the foamed resin substrate remain independent. Bubble state. Therefore, the foamed resin substrate of the present invention is a substrate with water resistance, artificial sebum and sweat resistance, static resistance and other properties that are hard to be damaged, and the stability of each performance is also very excellent.

In the present invention, the resin constituting the foamed resin substrate is not particularly limited. For example, from the viewpoint of water resistance or artificial sebum and sweat resistance, it is preferable to appropriately select a base polymer and a crosslinking agent having water resistance or oil resistance. Specific examples of the base polymer include: polyurethane resin which is a polymer of polyol and polyfunctional isocyanate; polyolefins such as polyethylene and polypropylene; styrene-butadiene-styrene -Block copolymers, styrene-isobutylene-styrene-block copolymers and other styrene-based block copolymers; ethylene-vinyl acetate, ethylene-ethyl acrylate, ethylene-methyl methacrylate and other vinyl copolymers Acrylic block copolymers such as methyl methacrylate-butyl acrylate-methyl methacrylate; acrylic copolymers obtained by copolymerizing 2-ethylhexyl acrylate or methyl acrylate; polychloride Halogenated polymers such as ethylene. Among them, in terms of static electricity resistance, heat resistance, artificial sebum and sweat resistance, flexibility, and impact resistance, polyurethane-based resins are preferred.

Polyurethane-based resins are generally resins containing the following parts: a soft segment, which contains polyol monomer units; and a hard segment, which contains polyfunctional isocyanate compounds or low molecular glycol monomer units.

The polyol used in the polyurethane resin is a compound having two or more hydroxyl groups. For example, the number of hydroxyl groups of the polyol is preferably close to 2 from the viewpoint of improving properties such as elastic elongation recovery of rubber. Specifically, the number of hydroxyl groups of the polyol is preferably 2 to 3, more preferably 2. As the polyol, for example, polyester polyol, polyether polyol, polycaprolactone polyol, polycarbonate polyol, castor oil-based polyol can be used. Two or more polyols can also be used in combination.

Polyester polyol is obtained, for example, by the esterification reaction of a polyol component and an acid component. Specific examples of polyol components include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5- Pentylene glycol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanedi Alcohol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylol Propane, pentaerythritol, hexanetriol, polypropylene glycol. Specific examples of acid components include: succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid Alkanoic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, o-phthalic acid Acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and their anhydrides.

Polyether polyols are, for example, water, low molecular weight polyols (such as propylene glycol, ethylene glycol, glycerol, trimethylolpropane, pentaerythritol), bisphenols (such as bisphenol A) or dihydroxybenzene (such as catechol) , Resorcinol, hydroquinone) as an initiator, and obtained by addition polymerization of ethylene oxide, propylene oxide, butylene oxide and other alkylene oxides. Specific examples include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Specific examples of polycaprolactone polyols include ring-opening polymers of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

Specific examples of polycarbonate polyols include: polycarbonate polyols obtained by polycondensation reaction of each of the above-mentioned polyol components with carbon chloride; Carbonic acid diesters such as ethyl, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethyl butyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, dibenzyl carbonate, etc. A polycarbonate polyol obtained by transesterification condensation; a copolymerized polycarbonate polyol obtained by using two or more of the above-mentioned polyol components in combination; the above-mentioned polycarbonate polyol and a carboxyl-containing compound Polycarbonate polyol obtained by esterification reaction; polycarbonate polyol obtained by etherification reaction of each of the above polycarbonate polyols and hydroxyl-containing compounds; each of the above polycarbonate polyols and ester compounds A polycarbonate polyol obtained by a transesterification reaction; a polycarbonate polyol obtained by subjecting each of the above polycarbonate polyols and a hydroxyl-containing compound to a transesterification reaction; each of the above polycarbonate polyols and a dicarboxylic acid Polyester-based polycarbonate polyol obtained by polycondensation of a compound; copolymerized polyether-based polycarbonate polyol obtained by copolymerizing each of the above-mentioned polycarbonate polyols with alkylene oxide.

The castor oil-based polyol is obtained by, for example, reacting castor oil fatty acid with each of the above-mentioned polyol components (for example, polypropylene glycol).

As the polyfunctional isocyanate compound used for the polyurethane resin, for example, a polyfunctional aliphatic isocyanate compound, a polyfunctional alicyclic isocyanate compound, and a polyfunctional aromatic isocyanate compound can be used. In addition, trimethylolpropane adducts of these compounds, biurets formed by reacting with water, and trimers having isocyanurate rings can also be used. Two or more polyfunctional isocyanate compounds can also be used in combination.

Specific examples of polyfunctional aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate Isocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate.

Specific examples of the polyfunctional alicyclic isocyanate compound include: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, and isophorone Diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated tetramethylxylylene Base diisocyanate.

Specific examples of polyfunctional aromatic diisocyanate compounds include: phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate Isocyanate, xylylene diisocyanate.

The polyurethane-based resin is obtained by curing a composition containing the above-described polyol and a polyfunctional isocyanate compound. In particular, from the viewpoint of properties such as rubber elastic elongation recovery rate, a linear polyester-based polyurethane resin with low crystallinity is preferred, and a hexylene glycol copolyester-based polyurethane resin is more preferred. Resin, polytetramethylene glycol-based polyurethane resin. As commercially available products of polyurethane resins, for example, there are trade names Sanprene manufactured by Sanyo Chemical Industry Co., Ltd., trade names Desmocoll manufactured by Sumika Bayer Urethane Co., Ltd., trade names NIPPOLLAN manufactured by Nippon Polyurethane Industry, etc., for example. Specifically, low crystallinity can be judged by the following operation: According to JIS K 6253 "Rubber Hardness Standards", make a resin test piece with a film thickness of 6mm, melt the test piece under the condition of 100℃×30 minutes, and place it in 23 Measure the time until the hardness of the resin becomes Shaw A90 after being placed in an environment of ±2°C and a relative humidity of 50±5%. Specifically, a resin whose time to become Shaw A90 is 72 hours or more can be referred to as a resin with low crystallinity. For example, the trade name Desmocoll 500 manufactured by Sumika Bayer Urethane is a highly crystalline resin that takes about 5 minutes to become Shaw A90, the trade name Desmocoll 540 is a highly crystalline resin that takes about 10 minutes, and the trade name Desmocoll 176 is 48. Crystalline resin in hours. On the other hand, Desmocoll 406 is a 72-hour low crystallinity resin.

唑啉系、三聚氰胺系之交聯劑。其中，就反應性、合成容易性、基材本身之柔軟性與耐衝擊性、及與黏著劑層之密接性等特性之觀點而言，較佳為異氰酸酯系交聯劑。尤其是就耐衝擊性之觀點而言，更佳為使用聚胺基甲酸酯系樹脂作為基礎聚合物，且與其一併使用異氰酸酯系交聯劑。 Furthermore, in the present invention, it is preferable to use a crosslinking agent from the viewpoint of improving the strength, heat resistance, and rubber elasticity of the base polymer. As the crosslinking agent, for example, metal chelate, metal alkoxide, epoxy, isocyanate, aziridine, polyfunctional acrylate, carbodiimide,

A crosslinking agent of oxazoline series and melamine series. Among them, from the viewpoint of reactivity, ease of synthesis, flexibility and impact resistance of the substrate itself, and adhesion to the adhesive layer, an isocyanate-based crosslinking agent is preferred. In particular, from the viewpoint of impact resistance, it is more preferable to use a polyurethane-based resin as a base polymer, and to use an isocyanate-based crosslinking agent together with it.

Other components may be added to the resin composition used to constitute the foamed resin substrate. Specifically, for example, you can add: catalysts, other resin components, adhesion imparting agents, inorganic fillers, organic fillers, metal powders, pigments, foils, softeners, plasticizers, anti-aging agents, heat sinks, conductive Agents, antioxidants, ultraviolet absorbers, light stabilizers, surface lubricants, leveling agents, anti-corrosion agents, heat-resistant stabilizers, polymerization inhibitors, slip agents, solvents. In particular, for the curing reaction, it is preferable to add a catalyst such as an organometallic compound or a tertiary amine compound. Specific examples of the organometallic compound include iron-based compounds, tin-based compounds, titanium-based compounds, zirconium-based compounds, lead-based compounds, cobalt-based compounds, zinc-based compounds, and bismuth-based compounds. In particular, from the viewpoint of reaction rate and environmental load, iron-based compounds and bismuth-based compounds are preferred.

The method of forming closed cells in the resin described above is not particularly limited, but it is preferably a method using foaming agents such as thermally expandable microcapsules, expanded hollow fillers, inorganic foaming agents, and organic foaming agents. . Among them, it is particularly preferable to use thermally expandable microcapsules and/or expanded hollow fillers.

As explained above, when the average diameter is as large as hundreds of μm or locally as large as 1~2mm as shown in Figure 2 (the conventional technology), there is a local shape In the case of a through state, the water resistance or static electricity resistance of the narrow-width processed foamed resin substrate adhesive tape becomes a big problem. Therefore, in the conventional technology, the operation of removing the extremely large independent bubbles is performed by the optical detector. However, the detection accuracy of the removal is not sufficient, so problems such as the deterioration of the yield caused by the lack of reliability or the deviation of the manufacturing batch, and the increase of the cost caused by the increase of the processing cost have arisen. On the other hand, if a foaming control method using thermally expandable microcapsules and/or expanded hollow fillers is adopted, the void diameter can be easily controlled to a smaller size within the specified range of the present invention.

Thermally expandable microcapsules are representative ones, which are mainly microspheres composed of a thermoplastic resin shell and liquid low-boiling hydrocarbons contained in the shell. The boiling point of the liquid low-boiling hydrocarbon is below the softening temperature of the thermoplastic resin constituting the shell. By heating and foaming the resin containing the thermally expandable microcapsules, closed cells can be formed. For example, heat-expandable microcapsules are dispersed in the resin used to form the substrate, so that the resin is thermally expanded to the extent that it does not break during thermoforming, and maintains the expanded shape after forming. Thereby, independent bubbles are formed in the resin. The average particle size of the thermally expandable microcapsules before expansion is preferably 5-50 μm, more preferably 10-30 μm, and the average particle size after expansion is preferably 30-150 μm, more preferably 40-120 μm. The thermal expansion start temperature of the thermally expandable microcapsules is preferably 100 to 170°C, the maximum foaming temperature is preferably 160 to 200°C, and the volume expansion rate is preferably about 50 to 100 times.

The thermoplastic resin constituting the outer shell of the heat-expandable microcapsule may be appropriately selected according to conditions such as the softening temperature or thermoforming temperature of the resin constituting the base material. Specific examples include homopolymers containing monomers such as (meth)acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; and containing two Copolymers of the above monomers. Binder resin can also be used to make titanium oxide, oxygen Inorganic particles such as zinc oxide, aluminum oxide, silicon dioxide, and calcium carbonate are fixed on the surface of the shell. In addition, acrylonitrile and silicon can be mainly used to form a shell, and the foaming characteristics (such as expansion rate) can be controlled by adjusting the amount of silicon blended.

The liquid low-boiling-point hydrocarbon contained in the thermally expandable microcapsules is preferably a hydrocarbon that vaporizes when the resin constituting the substrate is thermoformed. Specific examples include low-boiling liquids such as n-butane, isobutane, n-pentane, isopentane, and petroleum ether.

As commercial products of thermally expandable microcapsules, for example, there are trade names of Matsumoto Microsphere F-36D, F-36LVD, FN-80GSD, FN-100SD, FN-100MD, FN-100SSD, FN-105D, and FN-180SSD, etc., the trade names Expancel 053-40, 909-80, 930-120, etc. manufactured by EXPANCEL, and the trade names FINECELL MASTER MS401K, MS402K, MS405K, etc. manufactured by Dainichi Chemical Industry Co., Ltd.

The expanded hollow filler is formed by individually foaming heat-expandable microcapsules. Furthermore, only one of the thermally expandable microcapsules and the expanded hollow filler may be used, or both may be used in combination.

Specific examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, and sodium borohydride.

啉基-1,2,3,4-噻三唑等三唑系化合物；N,N'-二亞硝基五亞甲基四胺、N,N'-二甲基-N,N'-二亞硝基對苯二甲醯胺等N-亞硝基 系化合物。 Specific examples of organic blowing agents include: chlorofluoroalkanes such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodicarboxamide, and barium azodicarboxylate Azo compounds; p-toluenesulfonamide, diphenylsulfonium-3,3'-disulfonamide, 4,4'-oxybis(benzenesulfonamide), allylbis(sulfonamide) Equal hydrazine compounds; aminourea compounds such as ρ-methylphenylsulfacarbamide, 4,4'-oxybis(phenylsulfacarbazide); 5-

Linyl-1,2,3,4-thiatriazole and other triazole compounds; N,N'-dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'- N-nitroso compounds such as dinitroso-p-phthalamide.

The foamed resin substrate used in the present invention is a substrate in which closed cells are formed by foaming the resin. The expansion ratio is preferably 1.2 to 4 times, more preferably 2 to 3 times. The thickness of the foamed resin substrate is preferably 0.05 to 1.0 mm, more preferably 0.08 to 0.3 mm.

The foamed resin substrate can also be subjected to surface treatment to improve the adhesion with the adhesive layer or other layers. As the surface treatment, for example, corona treatment, flame treatment, plasma treatment, hot air treatment, and ozone can be cited. UV treatment, coating of easy bonding treatment agent. The degree of surface treatment can be judged, for example, based on the moisture permeability index obtained by the moisture permeability reagent. In terms of adhesion to the adhesive layer, the moisture permeability index of the surface of the substrate after surface treatment is preferably 36 mN/m or more, more preferably 40 mN/m, and particularly preferably 48 mN/m.

<Adhesive layer>

The adhesive layer is a layer containing the adhesive composition and is arranged on at least one side of the foamed resin substrate. The adhesive composition is not particularly limited as long as it contains an adhesive that does not impair the effect of the present invention. For example, it can be used: latex-based adhesives, solvent-based adhesives, oligomer-based adhesives, solid adhesives, and hot-melt adhesives.

The types of adhesives include, for example, acrylic adhesives, rubber adhesives (natural rubber adhesives or synthetic rubber adhesives), silicone adhesives, polyester adhesives, and urethane Ester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, and fluorine-based adhesives. Two or more adhesives can also be used in combination. In particular, from the viewpoint of characteristics such as heat resistance, cold resistance, water resistance, and artificial sebum and sweat resistance, an acrylic adhesive is preferred. Acrylic adhesive Generally, it is a composition containing a compound obtained by curing an acrylic copolymer [(meth)acrylate copolymer, etc.] as a base polymer with a crosslinking agent as a main component. Specifically, for example, the adhesive described in International Publication No. 2014/002203 can be preferably used.

The acrylic copolymer used in the acrylic adhesive is typically a (meth)acrylate copolymer having a hydroxyl group and a carboxyl group. Particularly preferably, it is obtained by copolymerizing at least four components of long-chain (meth)acrylic acid alkyl ester, carboxyl group-containing monomer, hydroxyl-containing monomer, and short-chain (meth)acrylic acid alkyl ester ( Meth)acrylate copolymer.

The long-chain (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms. Specific examples thereof include: butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylic acid Isooctyl ester, isononyl (meth)acrylate, lauryl (meth)acrylate. Specific examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, 2-carboxy-1-butene, 2-carboxy-1- Pentene, 2-carboxy-1-hexene, 2-carboxy-1-heptene. If the carboxyl group-containing monomer is used in an appropriate amount, the water resistance, load resistance and other properties will be improved. Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Short-chain (meth)acrylic acid alkyl esters are (meth)acrylic acid alkyl esters having an alkyl group of 1 to 3 carbon atoms, specifically, methyl (meth)acrylate and ethyl (meth)acrylate Esters, propyl (meth)acrylate. Among them, methyl acrylate is preferred.

In 100% by mass of the constituent components (monomer units) of the (meth)acrylate copolymer, the content of long-chain alkyl (meth)acrylate units is preferably 50 to 90 mass% %, more preferably 50 to 80% by mass. The content of the carboxyl group-containing monomer unit is preferably 3-20% by mass, more preferably 3-12% by mass. The content of the hydroxyl-containing monomer unit is preferably 3-20% by mass, more preferably 3-18% by mass. The content of the short-chain alkyl (meth)acrylate units is preferably 3-15% by mass, more preferably 3-12% by mass. Furthermore, the total content of the carboxyl group-containing monomer unit and the hydroxyl group-containing monomer unit is preferably 13% by mass or more. In addition, monomer units other than these four components may be included within a range that does not impair the effects of the present invention.

The acrylic copolymer system is obtained by copolymerizing several monomers. The polymerization method is not particularly limited. In terms of ease of polymer design, radical solution polymerization is preferred. In addition, an acrylic syrup containing an acrylic copolymer and its monomers may be prepared first, and a crosslinking agent and an additional photopolymerization initiator may be blended into the acrylic syrup to polymerize these.

The weight average molecular weight of the acrylic copolymer is preferably 700,000 to 2 million, more preferably 700 to 1.5 million. The lower limit of these ranges is meaningful in terms of load resistance and processability. In addition, the upper limit value is significant in terms of the coatability of the adhesive composition. The weight average molecular weight is a value obtained by measuring the gel permeation chromatography (GPC, Gel Permeation Chromatography) method.

The theoretical Tg of the acrylic copolymer is preferably -40°C or less, more preferably -50°C to -75°C. The theoretical Tg is a value calculated using the FOX formula. The main resin component of acrylic adhesive is acrylic copolymer, and other types of resin components can also be used in combination without compromising its characteristics.

The cross-linking agent used in the acrylic adhesive is a compound that reacts with the acrylic copolymer to form a cross-linked structure, and the representative one is a compound that can react with the carboxyl and/or hydroxyl group of the acrylic copolymer. Especially in terms of water resistance and load tolerance From the standpoint of properties such as weight, processability, impact resistance, artificial sebum resistance, and artificial sweat oil resistance, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred. These can also be used in combination. The blending amount of the crosslinking agent is preferably 0.001 to 1 part by mass relative to 100 parts by mass of the acrylic copolymer.

Specific examples of the isocyanate-based crosslinking agent include toluene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and modified prepolymers of these. Two or more of these can be used in combination. The compounding amount of the isocyanate-based crosslinking agent is preferably 0.02 to 1 part by mass, more preferably 0.05 to 0.2 part by mass relative to 100 parts by mass of the acrylic copolymer.

Specific examples of epoxy-based crosslinking agents include: N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylamine (Methyl) cyclohexane and other compounds having two or more epoxy groups. Two or more of these can be used in combination. The compounding amount of the epoxy-based crosslinking agent is preferably 0.001 to 0.5 parts by mass, and more preferably 0.001 to 0.1 parts by mass relative to 100 parts by mass of the acrylic copolymer.

To the adhesive, for example, an adhesive imparting agent, a plasticizer, a filler, and a coloring agent may be added. Specific examples of the adhesion imparting agent include rosin resins (rosin ester, polymerized rosin, disproportionated rosin ester, etc.), terpene phenol resin, terpene resin, petroleum resin, and styrene resin. As a specific example of the filler, silicon oxide can be cited. Specific examples of the coloring agent include carbon black, titanium oxide, aniline black, acetylene black, and Ketjen black. Moreover, for example, carbon black, carbon nanotubes, and black inorganic fillers may be added as light-shielding fillers.

The adhesive layer can be formed, for example, by coating an adhesive on a substrate, and crosslinking it by heating or ultraviolet irradiation. In addition, for example, an adhesive can be coated on release paper or other films, and the adhesive can be formed by cross-linking reaction by heating or ultraviolet irradiation. The adhesive layer is attached to one or both sides of the substrate. For the application of the adhesive, for example, a coating device such as a roll coater, a die nozzle coater, and a die lip coater can be used. In the case of heating after coating, the solvent in the adhesive composition can be removed while heating is used for the cross-linking reaction. The thickness of the adhesive layer is preferably 5 to 100 μm, more preferably 10 to 80 μm.

<Adhesive Tape>

The adhesive tape of the present invention has the above-described foamed resin substrate containing closed cells, and an adhesive layer provided on at least one side of the foamed resin substrate. It can be a single-sided adhesive tape provided with an adhesive layer on only one side of the substrate, but it is particularly preferably a double-sided adhesive tape provided on both sides.

As the substrate of the adhesive tape, it is preferable to use the above-described foamed resin substrate containing closed cells alone. However, within a range that does not impair the effects of the present invention, for example, a laminate formed by using another base material or other layers laminated on a foamed resin base material may be used as a base material.

According to IEC6100, the electrostatic resistance characteristic of the adhesive tape is preferably 15kV or more, more preferably 18kV or more. As explained above, it is believed that the anti-static property is generally affected by the type of resin, but when the type of resin is the same, it is estimated that the void diameter of the independent cells of the foamed resin substrate is controlled to a smaller size within a specific range. And it can improve the static electricity resistance. The value of the above-mentioned static electricity resistance is a value obtained by measuring the adhesive tape, and of course it is preferably the same measured value even when measuring the foamed resin substrate alone. The anti-static characteristic according to IEC6100 specifically means the following value, that is, as described in the following embodiment, the voltage value when a certain fixed voltage is fired 100 times in the width direction of the adhesive tape with an electrostatic gun and sparks are generated. .

The heating dimensional change rate of the adhesive tape is within 100% ± 5% when the size before heating is set to 100%, preferably ± 1% or less. The heating dimensional change rate (heat resistance) is more important in the application of the product when it is used or left at a high temperature. For example, the car navigation and other information portable terminals used around the front panel or dashboard of a car may have a temperature exceeding 80°C in summer. In this case, the base material of the adhesive tape that fixes the information display part of the car navigation system and the casing may shrink, which may cause peeling due to deformation. Moreover, in recent information portable terminals and other product applications that require high narrowing of the adhesive tape, such peeling at high temperatures is likely to occur. On the other hand, even if it is a narrow-width processed adhesive tape, as long as it shows the above-mentioned heating dimensional change rate, it is difficult to cause peeling even if it is used at a high temperature or placed under long-term vibration. From the viewpoint of such a heating dimensional change rate (heat resistance), it is preferable to use a polyurethane-based resin for the foamed resin substrate than a polyolefin-based resin. The heating dimensional change rate specifically means the dimensional change rate after heating the adhesive tape at 90° C. for 2 hours and leaving it at room temperature for 1 hour or more as described in the following examples.

The rubber elastic elongation recovery rate (2 times and 4 times) of the adhesive tape is 85% or more, preferably 90% or more. The rubber elastic elongation recovery rate is more important in the application of products that require secondary processability, repairability (elongation and peelability), and flexibility. The so-called repairability specifically refers to the following performance, that is, as described in the following examples, in a state where the surfaces of two rigid bodies are bonded to each other with a double-sided adhesive tape, one end of the adhesive tape is stretched to The adhesive tape is elongated and can be easily peeled off without any problems. For example, when a part of an information carrying terminal such as a smart phone or a mobile phone fails, it is desirable to easily peel off the adhesive tape that fixes the parts in order to exchange the parts, and there is no adhesive left in the peeled part. Residue. However, if the adhesive tape does not have moderate elasticity, even if one end of the adhesive tape is stretched, the adhesive layer will not fully stretch. Long, the adhesive force is not sufficiently reduced, and the adhesive tape will be broken halfway. On the other hand, even if it is an adhesive tape processed with a narrow width, as long as it is an adhesive tape that exhibits the recovery rate and high flexibility of the rubber elastic elongation recovery rate mentioned above, by stretching one end of the adhesive tape, The adhesive layer is also elongated continuously and uniformly, and the adhesive force is moderately reduced. As a result, it can be peeled off easily and without problems. Furthermore, the high degree of flexibility can cope with the unevenness, step difference, and deformation of the surface of the adherend, and also contribute to the improvement of adhesion, water resistance, impact resistance and other characteristics. The rubber elastic elongation recovery rate is specifically based on the following ratio, that is, as described in the following examples, the adhesive tape is stretched so that the length of the adhesive tape becomes 2 or 4 times, and 10 seconds after the tensile force is released The ratio of the recovery amount to the elongation at the time point.

The compressive deformation rate in the thickness direction of the adhesive tape is preferably 3.0% or more, more preferably 5.0% or more. The compressive deformation rate is important in the use of products where there are unevenness or step difference on the surface to be bonded, or the member itself is deformed. For example, when the information display component of a portable information terminal such as a smart phone or a mobile phone is attached to the casing, the bonded surface of each component is not necessarily flat, and there are usually unevenness or level differences. In addition, each member itself may be deformed during use. Therefore, if the adhesive tape cannot absorb the deformation, peeling occurs. On the other hand, even if it is an adhesive tape processed with a narrow width, as long as it is an adhesive tape exhibiting flexibility or stress relaxation like the above-mentioned compression deformation rate, it is difficult to peel off even in the above-mentioned case. The compression deformation rate is specifically the following ratio, that is, as described in the following examples, in accordance with the thickness test method of JIS Z 0237: 2000, the thickness of the dial gauge when the load is 20 kPa is used as the reference to increase the load The ratio of thickness change to 100kPa.

The interlayer strength of the entire adhesive tape with a foamed resin substrate is preferably 10N/10mm or more, more preferably 15N/10mm or more. The interlayer strength (90 degree peeling Separation adhesion) is more important in the use of products requiring secondary processing. The so-called secondary workability specifically means the performance that, as described in the following examples, when peeling the adhesive tape in the bonded state, it can be peeled off easily and without problems. For example, in the process of manufacturing information portable terminals such as smart phones or mobile phones, it is necessary to peel off the temporarily attached adhesive tape and perform the process again (for secondary processing). At this time, it is desired that the adhesive tape can be easily peeled, and no residue of adhesive or the like remains at the peeled portion. However, if the interlayer strength of the foamed resin substrate is low, although it also depends on the adhesive strength of the adhesive layer, the substrate itself is damaged when the adhesive tape is peeled off, or if the adhesive layer and the foamed substrate are If the adhesiveness (adhesion strength) is weak, it will cause interlayer peeling between the adhesive layer and the base material, and the residue will adhere to the adherend and be difficult to remove. On the other hand, if it is an adhesive tape including a foamed resin substrate having the above-mentioned interlayer strength, even if it is the above-mentioned situation, it is more difficult to cause damage than the conventional foamed resin substrate. Specifically, the interlayer strength is the 90-degree peel adhesion force obtained in accordance with JIS Z 0237 "Adhesive tape. Adhesive sheet test method" as described in the following examples.

The longitudinal and transverse tensile strength of the adhesive tape is preferably 6.0N/10mm or more. In addition, when the tensile strength of the foamed resin substrate alone is 100%, the tensile strength is preferably 110% or more. Furthermore, when one of the longitudinal and transverse tensile strengths is set to 100%, the other elongation is within 100%±15%. The elongation at break of the adhesive tape in the longitudinal and transverse directions is preferably 300% or more. Furthermore, when one of the elongation at break in the longitudinal direction and the transverse direction is set to 100%, the other elongation is within 100%±15%. Especially the case where the aspect ratio of the tensile strength and the elongation is small, it is more important in the application of the product requiring the frame-shaped adhesive tape formed by punching processing. For example, in the adhesive tape that fixes the information display part of the information portable terminal such as smart phone or mobile phone to the casing, the punching process is roughly quadrangular. There are more boxes. In this case, if the aspect ratio of tensile strength and elongation is large, deviation of physical properties will occur. On the other hand, if it is an adhesive tape with a small aspect ratio described above, it is difficult to produce deviations in physical properties regardless of the direction of punching. The tensile strength and elongation are specifically the strength and elongation at break when a tensile test is performed on an adhesive tape of a specific size as described in the following examples.

The loss coefficient (tanδ) of the adhesive tape at -20°C is preferably 0.20 or more, more preferably 0.3 or more. In addition, the storage elastic modulus at 85°C is preferably 2.0×10 ⁵ Pa or more, more preferably 2.5×10 ⁵ Pa or more, and the loss coefficient (tanδ) at 85°C is preferably 0.20 or more, more preferably 0.3 or more . The storage elastic modulus and loss coefficient are more important in the use of products requiring narrow adhesive tapes. For example, information portable terminals such as smartphones and mobile phones are constantly evolving due to the larger screen of the information display unit (display, etc.), the reduction of the entire product, and the improvement of design, so narrow adhesive tapes are required. In this case, if the storage elastic modulus or loss coefficient is low, there may be problems with adhesion. On the other hand, if it is an adhesive tape with the above-mentioned storage elastic modulus and loss coefficient, even if it is an adhesive tape processed with a narrow width, it is difficult to cause adhesion problems. The storage elastic modulus and loss coefficient are specifically the values obtained by measuring and calculating an adhesive tape with a thickness of 0.2mm between the parallel plates of the viscoelastic tester as described in the following examples. .

The above characteristics are mainly manifested by appropriately adjusting various conditions such as the type of resin of the foamed resin substrate, the size of closed cells, and the type of adhesive layer. Specific examples of the foamed resin substrate and the adhesive layer are as described above.

The width of the adhesive tape is not limited. However, from the viewpoint that all the properties obtained in the present invention are excellent and are particularly useful in narrow adhesive tapes, the width is preferably 0.5 to 5.0 mm, more preferably 0.7 to 3.0 mm. Also, the thickness of the adhesive tape is preferably 0.08 ~0.5mm, more preferably 0.1~0.4mm. In the case of punching processing (narrow processing) in order to make a narrow-width adhesive tape, it is better to design the product in such a way that the total thickness of the adhesive layer is not too much larger than the thickness of the base material to prevent adhesion The agent adheres or overflows to the punching knife.

[Example]

Hereinafter, the present invention will be further described in detail through examples. In the following description, "parts" means "parts by mass".

<Preparation of Acrylic Adhesive Composition>

Mix 75 parts of 2-ethylhexyl acrylate, 10 parts of methyl acrylate, 10 parts of acrylic acid, and 5 parts of 2-hydroxyethyl acrylate in a reaction device equipped with a stirrer, a thermometer, a reflux cooler, and a nitrogen introduction tube. And add ethyl acetate, n-dodecyl mercaptan as a chain transfer agent and 0.1 part of lauryl peroxide as a radical polymerization initiator. Nitrogen was sealed in the reaction device, and while stirring, polymerization was carried out at 68°C for 3 hours under nitrogen gas flow, and then at 78°C for 3 hours.

After that, it was cooled to room temperature and ethyl acetate was added. By this, an acrylic copolymer with a solid content concentration of 30%, a theoretical Tg of 64.8, and a weight average molecular weight of 1.1 million was obtained. Then, 0.07 parts of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry, trade name Corona L) and an appropriate amount of organic solvent were added to 100 parts of the acrylic copolymer, and stirred with a mixer until it became uniform to obtain an acrylic Adhesive composition.

<Preparation of polyurethane resin composition>

Add appropriate amount of organic solvent to powdery ingredients such as foaming agent and coloring agent, and use The blender performs dispersion. Then, the polyurethane-based resin solution and the crosslinking agent are added, and the mixture is stirred with a mixer until uniformly dispersed, thereby obtaining a polyurethane-based resin composition. The amounts (parts) of each component are shown in Tables 1 and 2.

<Examples 1 to 8 and Comparative Examples 1 to 2>

Apply the polyurethane resin composition to one side of a release paper with a silicone release agent formed on both sides, and dry it at 70°C for 2 minutes + 90°C for 2 minutes to remove the solvent . Then, it foamed by heating at 130 degreeC for 2 minutes, and it was wound up. Furthermore, maturation was performed at 40°C for 3 days to complete the curing reaction, and a foamed resin substrate (thickness 0.10 mm) was obtained.

The above-mentioned acrylic adhesive composition is coated on a release paper with a silicone release treatment on both sides and dried to form an adhesive layer. Then, the foamed resin substrate was subjected to corona discharge treatment on one side, and the adhesive layer was attached to the other side. Furthermore, the adhesive layer was also attached to the opposite side of the foamed resin substrate by the same method. Thereafter, the curing reaction of the adhesive layer was completed at 40°C for 3 days to obtain a double-sided adhesive tape with a thickness of about 0.20 mm (the thickness of each adhesive layer was about 50 μm).

<Comparative Example 3>

Except for using polyethylene (PE, polyethylene) foam (manufactured by Sekisui Chemical Co., Ltd., trade name VOLARA XL-H black #1001) as the base material, a double-sided adhesive with a thickness of approximately 0.20 mm was produced in the same manner as in Example 1. Tape (the thickness of the adhesive layer on each side is about 50μm).

<Comparative Example 4>

Except for using a polyethylene terephthalate (PET, polyethylene terephthalate) film (manufactured by Toray, trade name Lumirror S-10) as a substrate, a double-sided thickness of approximately 0.20 mm was produced in the same manner as in Example 1. Adhesive tape (the thickness of the adhesive layer on each side is about 75μm).

<Comparative Example 5>

The acrylic adhesive composition of Example 1 was coated on release paper so as to have a thickness of 0.2 mm to produce a substrate-free double-sided tape with a thickness of 0.20 mm.

<Test method>

The following tests were performed on the double-sided adhesive tapes obtained in Examples and Comparative Examples. The results are shown in Tables 1 to 3.

[Void diameter]

Observe the multiple independent bubbles in the 5×5mm area of the foamed resin substrate by using the optical microscope of the transmission method, and measure the average value and the maximum value of the void diameter.

[Rubber elastic elongation recovery rate]

The double-sided adhesive tape was cut into a width of 10 mm and a length of 150 to 200 mm, and the adhesiveness was inactivated by calcium carbonate, and the resultant was used as a test piece. Fix one end of the test piece in a tensile testing machine with the chuck spacing set to 100mm, and mark both sides with a test amount of 100mm in length with marking ink. Stretching at a speed of 1500mm/min, when the length becomes 2 times (elongation 100mm) or 4 times (elongation 300mm) Open a chuck, and measure the total length of the marked part at the point when 10 seconds have elapsed (total length at the time of recovery). Then, the ratio of the amount of recovery (total length at the time of extension-total length at the time of recovery) to the amount of extension was determined, and this was taken as the rubber elasticity extension recovery rate. The specific calculation method is as follows.

2 times elongation recovery rate (%)=(200-total length when recovering)÷100×100

4 times elongation recovery rate (%)=(400-total length when recovering)÷300×100

[Heating dimensional change rate]

The double-sided adhesive tape was cut into 100×100 mm, and the adhesiveness was inactivated by calcium carbonate, and the resultant was used as a test piece. The test piece was hung in a dryer at 90°C for 2 hours, and then left at room temperature for more than 1 hour to measure the size. The specific calculation method of the heating dimensional change rate is as follows.

Heating size change rate (%)=[(size after heating)-(size before heating)]÷(size before heating)×100

[Narrow width processability]

Cut the double-sided adhesive tape into 10 pieces with a width of 5mm and a length of 125mm and keep them in the same state (that is, the adhesive tapes made by the slits maintain their adjacent state when they are broken), at 65℃, 80% Place for 1 day under an atmosphere of Relative Humidity (RH). Then, each piece was peeled off together with the release paper in the 180-degree direction, and adhesion to the adjacent part was visually confirmed, and the narrow width processability was evaluated using the following criteria.

"○": There is almost no adhesion to the adjacent part, and it can be peeled without peeling off the adjacent part.

"×": There is significant adhesion to the adjacent part, and the adjacent part is peeled off at the same time.

[Secondary processing]

Use aluminum foil (0.08mm thick) on one side of the double-sided adhesive tape as a substrate as a test piece. According to JIS Z 0237 "Adhesive Tape. Adhesive Sheet Test Method", the adhesive tape is attached to stainless steel The 90-degree peel test after 30 minutes of the board was evaluated using the following criteria.

"○": No interlayer damage or paste residue of the substrate.

"×(a)": Breakage occurs between the layers of the substrate during peeling.

"×(b)": After peeling, the paste remains on the stainless steel plate.

[Load resistance]

Cut the double-sided adhesive tape to a size of 25×25mm, and peel off a release paper. Stick the double-sided adhesive tape on the test hook board (HOOK BOARD), then peel off another release paper, and stick it on the polycarbonate board. Then, a load of 700 gf was applied to the hook, maintained at 85°C for 60 minutes, and the load resistance was evaluated using the following criteria.

"○": The hook has not fallen for 60 minutes.

"×": The hook falls within 60 minutes.

[Impact resistance]

Cut the double-sided adhesive tape into a 50×45mm frame with a width of 0.8mm. Peel off a release paper and stick it on a 2mm thick glass plate. Then peel off another release paper and stick it on a 3mm thick polycarbonate. board. Then, using an autoclave, pressure treatment was performed at 23° C. and 0.5 MPa for 1 hour. Furthermore, use SUS board to adjust the overall weight It is 250g, placed at -20°C for more than 1 hour. Then, from a height of 1.5m, make the test panel pass through the tube in a vertical direction and drop to the concrete floor, and measure until the glass panel peels off or breaks (A), or until the interlayer failure of the substrate occurs (B ) The number of drops.

[Waterproof]

Cut the double-sided adhesive tape into a frame shape of 40×50mm with a width of 0.8mm. Peel off a release paper and attach it to a 2mm thick glass plate. Then peel off another release paper and attach it to a 2mm thick glass plate. Then, the sample was subjected to pressure treatment (0.5 MPa) at 23°C for 1 hour using an autoclave. Thereafter, based on the waterproof standard IEC "International Electrical Standards Conference" 60529: 2001 [Equivalent standard: JIS C 0920: 2003 "Degrees of protection provided by enclosures (IP code)" ] IPX7 test method, the sample is immersed in water, and the water resistance is evaluated. In addition, use an autoclave for other samples and pressurize them at 23°C for 1 hour. Then, based on the IPX8 test method of the above waterproof specification, the other samples were submerged in water of 0.1MPa, 0.25MPa, and 0.5MPa respectively. , And evaluate water resistance. The evaluation is carried out in the following grades. That is, the above-mentioned water resistance is the water resistance that meets the conditions specified by the protection level IPX8 to the conditions specified by the IPX7.

In addition, the width of the double-sided adhesive tape was changed to 2 mm, and one ultra-fine copper wire with a diameter of 0.04 mm was inserted into a bonding surface for bonding. Other than that, the same test was performed. This evaluation is an evaluation of the waterproofness in a state where foreign matter (extremely thin copper wire) exists on the joint surface.

[Resistant to artificial sebum. Artificial sweat oiliness]

Cut the double-sided adhesive tape into a frame shape of 40×50mm with a width of 0.8mm. Peel off a release paper and attach it to a 2mm thick glass plate. Then peel off another release paper and attach it to a 2mm thick glass plate. Then, using an autoclave, pressure treatment was performed at 23° C. and 0.5 MPa for 1 hour. The sample was immersed in artificial sebum (triolein 33.3%, oleic acid 20.0%, squalene 13.3%, myristyl octalaurate 33.4%) or artificial sweat oil for 1 hour. The sample was taken out, and allowed to stand for 72 hours in an environment of 85° C. and 85% RH, and then placed in a normal environment for 240 hours. Observe the sample visually, and use the following criteria to resist artificial sebum. The oiliness of artificial sweat is evaluated.

"○": Stripping without tape.

"×": There is stripping.

[Antistatic characteristics]

A double-sided adhesive tape with a width of 0.7 mm was used as a test piece. As shown in FIG. 3, a double-sided adhesive tape 1 was arranged between the high voltage (HV) electrode 2 and the touch pattern simulation electrode 3. The electrodes 2 and 3 are wired on a test element group (TEG) substrate 4, and the TEG substrate 4 is placed on a SUS platform 6 with an insulating sheet 5 interposed therebetween. The touch pattern analog electrode 3 and the SUS platform 6 are grounded. Furthermore, as shown in FIG. 4, the acrylic board 7 was covered on the test surface. Then, according to IEC61000-4-2, an electrostatic gun is used to shoot a certain fixed voltage to the HV electrode 2 100 times, and the voltage value when a spark is emitted toward the analog electrode 3 of the touch pattern is measured.

[Repairability]

Between two polycarbonate plates (50×50mm), a double-sided adhesive tape with a width of 10mm is attached so that one end becomes about 10mm longer than the polycarbonate board. About 30 minutes After the clock, whether the one end portion can be stretched and the belt can be peeled off for a test, and evaluated using the following criteria.

"○": Extensible peeling.

"△": When the elongation speed is slowed down, it can be stretched and peeled.

"×": Belt fracture occurred.

[Tensile strength and elongation (tape/substrate) and its aspect ratio]

Cut the foamed resin substrate and the double-sided adhesive tape into widths of 10mm and length of 200mm, respectively, and fix them on a tensile testing machine with the chuck spacing set to 100mm. Stretch them at a speed of 300mm/min to measure the break The strength (N/10mm) and elongation (%). Furthermore, the double-sided adhesive tape is cut so that the horizontal length becomes 200mm, the strength and elongation are measured under the same conditions, and the aspect ratio of each measured value is calculated [(horizontal tensile strength and elongation/longitudinal Tensile strength and elongation)×100]%.

[Compression Deformation Rate]

According to the thickness test method of JIS Z 0237:2000 "Adhesive Tape. Adhesive Sheet Test Method", the thickness of double-sided adhesive tape is measured when the load of the dial gauge is small (20kPa) and when the load is large (100kPa) . Then, use the calculation formula of compression deformation rate (%)=[(thickness at 100kPa pressure)-(thickness at 20kPa pressure)]÷(thickness at 20kPa pressure)×100 to calculate the compression deformation rate.

[Storage elastic modulus and loss coefficient]

In order to perform dynamic viscoelasticity measurement, a viscoelasticity testing machine is used to pinch a double-sided adhesive tape with a thickness of about 0.2mm between the parallel plates of the measuring part of the testing machine. The storage elastic modulus (G') and loss elastic modulus (G") from -50°C to 150°C are measured at 1Hz. Furthermore, the loss coefficient is calculated using the calculation formula of loss coefficient (tanδ)=G"/G'.

[UE1]: Low crystallinity linear polyester urethane elastomer (manufactured by Nippon Polyurethane Industry, trade name NIPPOLLAN 2304)

[UE2]: Linear polyester urethane elastomer with low crystallinity (manufactured by Sumika Bayer Urethane, trade name Desmocoll 406)

[UE3]: Linear polyester urethane elastomer with low crystallinity (manufactured by Sanyo Chemical Co., Ltd., trade name Sanprene LQ-540)

[UE4]: Linear polyester urethane elastomer with low crystallinity (Sanyo Chemical Manufactured by an industrial company, trade name Sanprene IB-129)

[UE5]: Medium crystallinity linear polyester urethane elastomer (manufactured by Sumika Bayer Urethane Company, trade name Desmocoll 176)

[UE6]: High crystallinity linear polyester urethane elastomer (manufactured by Sumika Bayer Urethane, trade name Desmocoll 500)

"SIBS": Synthetic rubber containing styrene-isobutylene-styrene copolymer (manufactured by Kaneka Co., Ltd., trade name SIBSTAR)

[CR]: Isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry, trade name Corona L)

[FA1]: Heat-expandable foaming agent (manufactured by Matsumoto Oil Pharmaceutical Co., Ltd., trade name FN100SSD)

[FA2]: Expanded foaming agent (manufactured by Japan Fillite, trade name 920DE40d30)

[CB]: Carbon black (manufactured by Denka Chemical Industry Co., Ltd., trade name DENKA BLACK HS100)

<evaluation>

From the results shown in Tables 1 to 3, it is clear that the adhesive tapes of Examples 1 to 8 are excellent in each characteristic. Furthermore, the adhesive tapes of Examples 4 and 5 have poor repairability (elongation and peelability). However, since the adhesive tapes of Examples 4 and 5 had low tensile strength, the tape was broken during elongation and peeling. In addition, the adhesive tapes of Examples 4 and 5 are excellent in other properties such as static electricity resistance.

On the other hand, the adhesive tapes of Comparative Examples 1 and 2 have too low rubber elastic elongation recovery rate. Therefore, even if the tensile strength of the adhesive tape is sufficient, the adhesive tapes are produced during elongation and peeling The raw belt is broken. Comparative Examples 1 and 2 are very different from Examples 4 and 5 in this respect.

The adhesive tape of Comparative Example 3 is an example of using a PE-based foamed resin substrate in which the void diameter of the bubbles is too large, and the properties such as static resistance characteristics are poor. The adhesive tape of Comparative Example 4 is an example in which a non-bubble PET film is used as the base material, and the characteristics such as impact resistance are poor. The adhesive tape of Comparative Example 5 is an example of a baseless double-sided adhesive tape without a base, and has poor impact resistance and other properties.

(Industrial availability)

For example, the adhesive tape of the present invention has excellent water resistance, so even if the machine is submerged in water or high water pressure is applied, it is difficult for water to penetrate into the interior, which can reduce the occurrence of machine malfunctions. In addition, due to its excellent anti-static properties, even if a user with static electricity touches the machine, it is difficult for static electricity to pass through the adhesive tape, and it is difficult for the internal parts to be damaged. In addition, due to its excellent heat resistance and impact resistance, even if the machine is used or left under high temperature, or is subjected to impact, it is difficult to cause problems. In addition, since it has excellent repairability (elongation and peelability), it is easy to exchange parts during machine repair. Therefore, the adhesive tape of the present invention is especially suitable for forming smart phones, mobile phones, electronic notebooks, personal handy-phone systems (PHS, Personal Handy-phone System), tablet personal computers (PC, personal computer), digital cameras, music Players, portable TVs, notebook computers, game consoles and other portable information terminal equipment components are very useful for bonding or fixing purposes. Especially for the connection of the protection panel of the information display part (display, etc.) of the smart phone or mobile phone to the frame, or the fixing of the module (battery, etc.) of the machine, a thinner and thinner adhesive tape is required. It can be better used in the application.

Claims (9)

An adhesive tape, which has a foamed resin substrate containing closed cells and an adhesive layer provided on at least one side of the foamed resin substrate. The average diameter of the closed cells is 20~180μm, and the maximum diameter is Below 300μm, the heating dimensional change rate after heating the adhesive tape at 90℃ for 2 hours is within 100%±5% when the size before heating is set to 100%. The rubber elastic elongation recovery rate of the above adhesive tape 85% or more; the foamed resin substrate contains polyurethane resin as the base polymer; the adhesive layer is composed of acrylic adhesives, rubber adhesives, silicone adhesives, and poly A layer composed of an adhesive composition of ester adhesive, urethane adhesive, polyamide adhesive, epoxy adhesive, vinyl alkyl ether adhesive or fluorine adhesive; The above-mentioned heating dimensional change rate is the rate of dimensional change after heating the adhesive tape at 90°C for 2 hours and placing it at room temperature for more than 1 hour; the above-mentioned rubber elastic elongation recovery rate is such that the length of the adhesive tape becomes twice or Stretching is carried out in a 4-fold way, and the ratio of the amount of recovery to the amount of elongation at 10 seconds after releasing the stretching force. Such as the adhesive tape of claim 1, wherein the polyurethane resin is a linear polyester polyurethane resin with low crystallinity. Such as the adhesive tape of claim 1, which is a double-sided adhesive tape provided with an adhesive layer on both sides of the foamed resin substrate. Such as the adhesive tape of claim 1, wherein the longitudinal and transverse tensile strength is 6.0N/10mm or more, and the tensile strength is 110% when the tensile strength of the foamed resin substrate alone is set to 100% Above, when one of the longitudinal and transverse tensile strength is set to 100%, the other tensile strength is within 100%±15%, and the longitudinal and transverse tensile strength is broken The elongation at break is more than 300%. When one of the longitudinal and transverse elongation at break is set to 100%, the other elongation is within 100%±15%; the above tensile strength The foamed resin substrate and the adhesive tape were cut into widths of 10mm and length of 200mm, respectively, and fixed to a tensile testing machine with the chuck spacing set to 100mm, and stretched at a speed of 300mm/min. The value of strength (N/10mm) and elongation (%) at break. Such as the adhesive tape of claim 1, in which the electrostatic resistance characteristic according to IEC6100 is 15kV or more. Such as the adhesive tape of claim 1, wherein the compression deformation rate in the thickness direction is above 3.0%. For example, the adhesive tape of claim 1, wherein the loss coefficient at -20°C is 0.20 or more, the storage elastic modulus at 85°C is 2.0×10 ⁵ Pa or more, and the loss coefficient at 85°C is 0.20 or more; the storage elasticity mentioned above The modulus and loss coefficient are the values obtained by measuring and calculating an adhesive tape with a thickness of 0.2mm between the parallel plates of the viscoelasticity testing machine and measuring and calculating at a frequency of 1 Hz. For example, the adhesive tape of claim 1, which is used for bonding or fixing the components constituting the portable information terminal machine. A method for manufacturing an adhesive tape, which is used to manufacture the adhesive tape of claim 1, and has a step of obtaining a foamed resin substrate by forming independent bubbles using thermally expandable microcapsules and/or expanded hollow fillers.

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